When to bind two scores together

When music for two or more instruments is issued
as two scores and the scores are not issued together (e.g.,
the 300 field says "1 score") follow these instructions:

M1011, M1111:
When we get two 2-piano scores, they should never be bound together.
When we a solo piano part and one 2-piano score, they should be bound together.

Other class numbers:
When music for two or more instruments is issued in scores published singly,
and we purchase enough for performance, bind all together. For example, when
we buy two copies of a score for two violins, the 300 field will say "1 score."
Assign only one barcode, even though we have two copies.